what charge controller do I need for a 250watt panel
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I am getting 5.6 sun hours from http://goo.gl/5O4zGQ . the actual reading is for GHANA as @russ stated.
the 4.0 Kwh I gave already includes the fudge factor.Comment
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I am getting 5.6 sun hours from http://goo.gl/5O4zGQ . the actual reading is for GHANA as @russ stated.
the 4.0 Kwh I gave already includes the fudge factor.MSEE, PEComment
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Then how do explain 714 watts?
[4 Kwh x 1.5] / 5.6 = 1071 Watts, not 714. Round that up to 1100 or even better 1200 and use 200 watt panels. Do not use a Prime number of panels like 5, 7, 11.....
Here is the deal. If you are fortunate enough to live in a area that actually gets 5.6 Sun Hours in the shortest month, the design process changes for panel wattage calculations. Once you go above 4.4 Sun Hours you fail to meet the C/12 minimum charge rate of FLA batteries.
That leaves you two options.
1. Use AGM batteries which do not need a minimum charge rate.
2. Provide a panel wattage that meets the minimum C/12 charge requirement. Put another way you over size the panel wattage to get to C/12 minimum requirement.
Don't be fooled into think Going AGM will be less expensive because you would be dead wrong. AGM batteries cost twice as much as FLA and only last half as long. Much less expensive to up the panel wattage and charge controller size. Doing that also means a lot less generator run time during the year.
So for example if you require 4 Kwh per day or a 24 volt 800 AH battery minimum panel wattage is 1700 watts and a 63 amp CC. Odd numbers so go to 1800 watts and 80 amp CC. That gives you room to grow.
Better yet and less expensive is 48 volt battery @ 400 AH, 1800 watt panel with 40 amp MPPT controller. Still the same battery capacity and panel wattage, but a much smaller less expensive controller requiring smaller wiring.
You got to cover all angles to find the least expensive route.MSEE, PEComment
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I mean 24v at noon on a bright sunny day isn't something he should be seeing unless he's done something wrong or the neighbors played a trick on him by covering his panels with a tarp all morning.Comment
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I don't think the problems my math, issue is that this imaginary system of yours is fubar.
I mean 24v at noon on a bright sunny day isn't something he should be seeing unless he's done something wrong or the neighbors played a trick on him by covering his panels with a tarp all morning.MSEE, PEComment
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so badly that it's just managing to get up to 50% DOD at high noon on a beautiful sunny day.Comment
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Easy, with 3 days on rainy season without sun, the SOC of the battery gone straight down to 30%. one morning can't charge it up to 80% SOC.Comment
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Which is the same thing Sunking would recommend when he isn't giving a sales pitch for MPPT.Comment
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Actually most off grid people in Jamaica do the two days capacity for the battery, so the system cost will be much less as the battery bank s smaller, we don't afraid to fire up the generator when is raining.Comment
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Then how do explain 714 watts?
[4 Kwh x 1.5] / 5.6 = 1071 Watts, not 714. Round that up to 1100 or even better 1200 and use 200 watt panels. Do not use a Prime number of panels like 5, 7, 11.....
Here is the deal. If you are fortunate enough to live in a area that actually gets 5.6 Sun Hours in the shortest month, the design process changes for panel wattage calculations. Once you go above 4.4 Sun Hours you fail to meet the C/12 minimum charge rate of FLA batteries.
That leaves you two options.
1. Use AGM batteries which do not need a minimum charge rate.
2. Provide a panel wattage that meets the minimum C/12 charge requirement. Put another way you over size the panel wattage to get to C/12 minimum requirement.
Don't be fooled into think Going AGM will be less expensive because you would be dead wrong. AGM batteries cost twice as much as FLA and only last half as long. Much less expensive to up the panel wattage and charge controller size. Doing that also means a lot less generator run time during the year.
So for example if you require 4 Kwh per day or a 24 volt 800 AH battery minimum panel wattage is 1700 watts and a 63 amp CC. Odd numbers so go to 1800 watts and 80 amp CC. That gives you room to grow.
Better yet and less expensive is 48 volt battery @ 400 AH, 1800 watt panel with 40 amp MPPT controller. Still the same battery capacity and panel wattage, but a much smaller less expensive controller requiring smaller wiring.
You got to cover all angles to find the least expensive route.
2,500 wh x 1.5 = 3,750 wh rounded up to 4,000 wh = 4.0 kwh
then 4,000 wh / 5.6 h = 714 wattsComment
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I usually run my plex media server from my desktop. but do you think the desktop pulls all that 250 watts from its power supply esp when it's idle or normal operations? if not then i guess i would have to go with your suggestion.Comment
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